Resistance of narrow diffused layers

The resistance evaluation of very narrow diffused layers is described. A two-dimensional analysis of the diffused layer conductance has been made using a numerical technique. A substantial reduction of the effective sheet resistance is shown to occur when the width of a diffusion mask window is narrowed relative to the junction depth. This indicates that the conductance of such narrow layers is influenced predominantly by the lateral diffusion effect, and that the geometrical effect of diffusion mask on the vertical impurity penetration can be almost neglected. The experimental data are in good agreement with this result. Design curves are presented to determine the resistance accurately, which are useful for the design of high-value resistors in integrated circuits.